Sudden Cardiac Death and Ventricular Arrhythmias in Hypertrophic Cardiomyopathy

Risk profiles for ventricular arrhythmias in hypertrophic cardiomyopathy through clustering analysis including left ventricular strain

AIMS

The prediction of ventricular arrhythmia (VA) in hypertrophic cardiomyopathy (HCM) remains challenging. We sought to characterize the VA risk profile in HCM patients through clustering analysis combining clinical and conventional imaging parameters with information derived from left ventricular longitudinal strain analysis (LV-LS).

METHODS

A total of 434 HCM patients (65% men, mean age 56 years) were included from two referral centers and followed longitudinally (mean duration 6 years). Mechanical and temporal parameters were automatically extracted from the LV-LS segmental curves of each patient in addition to conventional clinical and imaging data. A total of 287 features were analyzed using a clustering approach (k-means). The principal endpoint was VA.

RESULTS

4 clusters were identified with a higher rhythmic risk for clusters 1 and 4 (VA rates of 26%(28/108), 13%(13/97), 12%(14/120), and 31%(34/109) for cluster 1,2,3 and 4 respectively). These 4 clusters differed mainly by LV-mechanics with a severe and homogeneous decrease of myocardial deformation for cluster 4, a small decrease for clusters 2 and 3 and a marked deformation delay and temporal dispersion for cluster 1 associated with a moderate decrease of the GLS (p < 0.0001 for GLS comparison between clusters). Patients from cluster 4 had the most severe phenotype (mean LV mass index 123 vs. 112 g/m2; p = 0.0003) with LV and left atrium (LA) remodeling (LA-volume index (LAVI) 46.6 vs. 41.5 ml/m2, p = 0.04 and LVEF 59.7 vs. 66.3%, p < 0.001) and impaired exercise capacity (% predicted peak VO2 58.6 vs. 69.5%; p = 0.025).

CONCLUSION

Processing LV-LS parameters in HCM patients 4 clusters with specific LV-strain patterns and different rhythmic risk levels are identified. Automatic extraction and analysis of LV strain parameters improves the risk stratification for VA in HCM patients.

How are the predictors of sudden death modified after septal myectomy surgery?

BACKGROUND

Hypertrophic cardiomyopathy is a condition associated with an increased risk of sudden death compared to the general population. Extended septal myectomy surgery has been suggested to impact the reduction of sudden death events according to various publications. The aim of this study was to assess changes in the prevalence of sudden death predictors in a population of patients undergoing extended septal myectomy surgery.

METHODS

Ninety-four consecutive patients underwent extended septal myectomy surgery due to symptomatic hypertrophic cardiomyopathy. Risk factors for sudden death, as defined by the American Heart Association and the European Society of Cardiology, were evaluated before and three months after surgery.

RESULTS

The mean age of the population was 57 ± 13 years. A significant reduction was observed in the maximum septal thickness from 21.3 to 14 mm (p<0.001), along with a decrease in the anteroposterior diameter of the left atrium from 51 to 47 mm (p=0.021). Resting intraventricular gradients decreased from 49.2 to 6.4 mmHg (p<0.001), and Valsalva-induced gradients decreased from 93.9 to 8.7 mmHg (p<0.001). Non-sustained ventricular tachycardia decreased from 6% to 2% (p<0.001), and atrial fibrillation decreased from 30% to 15% (p<0.001). Ischemic behavior during exercise stress echo decreased from 6% to 0%, and the European Society of Cardiology sudden death risk score reduced from 3.32 to 1.44 (p<0.001).

CONCLUSIONS

In this cohort of hypertrophic cardiomyopathy patients, extended septal myectomy surgery was associated with a reduction in the number and magnitude of sudden death predictors, potentially explaining the reduced mortality reported in the literature.

Arrhythmias and Hypertrophic Cardiomyopathy: Unravelling the Connection

Hypertrophic cardiomyopathy (HCM) results from gene mutations affecting cardiac sarcomeres and is inherited in an autosomal dominant manner. With a prevalence of 1:200-1:500 in the general population, HCM is characterised by a hypertrophied and non-dilated left ventricle with predominant involvement of the interventricular septum. The myocardium's structural and intracellular factors, combined with triggers such as physical exertion, autonomic dysfunction, and ischemia, can lead to reentry events, and atrial and ventricular arrhythmias, including atrial fibrillation (AF) which is common among HCM patients. To manage the increased risk of mortality arising from congestive heart failure and thromboembolism, in patients with AF long-term anticoagulation and antiarrhythmic drugs are employed. HCM patients may also encounter supraventricular and ventricular arrhythmias, such as nonsustained ventricular tachycardia and ventricular premature beats, which can potentially lead to sudden cardiac death and necessitate treatment with implanted defibrillators. Physicians must comprehensively analyse clinical, anatomical, hemodynamic, rhythmic, functional, and genetic characteristics to identify HCM patients at high risk of sudden death. This article aims to discuss the pathophysiology of arrhythmia in HCM and clinical recommendations for various ventricular and atrial fibrillation including catheter ablation and implantable cardioverter-defibrillator (ICD).

Hypertrophic Cardiomyopathy in a Latin American Center: A Single Center Observational Study

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a complex disorder that includes various phenotypes, leading to different manifestations. It also shares different disadvantages typical of rare diseases, including limited recognition, lack of prospective studies assessing treatment, and little or delayed access to advanced treatment options. Reliable data about the prevalence and natural history of cardiomyopathies in South America are lacking. This study summarizes the features and management of patients with HCM in a university hospital in Colombia.

METHODS

This was an observational retrospective cohort study of patients with HCM between January 2010 and December 2021. Patient data were analyzed from an institutional cardiomyopathy registry. Demographic, paraclinical, and outcome data were collected.

RESULTS

A total of 82 patients during the study period were enrolled. Of these, 67.1% were male, and the mean age at diagnosis was 49 years. Approximately 83% were in NYHA functional class I and II, and the most reported symptoms were dyspnea (38%), angina (20%), syncope (15%), and palpitations (11%). In addition, 89% had preserved left ventricular ejection fraction (LVEF) with an asymmetric septal pattern in 65%. Five patients (6%) had alcohol septal ablation and four (5%) had septal myectomy. One patient required heart transplantation during follow-up. Sudden cardiovascular death was observed in 2.6%. The overall mortality during follow-up was 7.3%.

CONCLUSIONS

HCM is a complex and heterogeneous disorder that presents with significant morbidity and mortality. Our registry provides comprehensive data on disease courses and management in a developing country.

New Insights into the Role of Ferroptosis in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the principal cause of disease burden and death worldwide. Ferroptosis is a new form of regulated cell death mainly characterized by altered iron metabolism, increased polyunsaturated fatty acid peroxidation by reactive oxygen species, depletion of glutathione and inactivation of glutathione peroxidase 4. Recently, a series of studies have indicated that ferroptosis is involved in the death of cardiac and vascular cells and has a key impact on the mechanisms leading to CVDs such as ischemic heart disease, ischemia/reperfusion injury, cardiomyopathies, and heart failure. In this article, we reviewed the molecular mechanism of ferroptosis and the current understanding of the pathophysiological role of ferroptosis in ischemic heart disease and in some cardiomyopathies. Moreover, the comprehension of the machinery governing ferroptosis in vascular cells and cardiomyocytes may provide new insights into preventive and therapeutic strategies in CVDs.

Long-term nifekalant use in a patient with dilated cardiomyopathy and recurrent ventricular tachycardia

The potential utility of nifekalant, a new Class III antiarrhythmic drug, to offer long-term protection against ventricular arrhythmia has been investigated in this case report. A 44-year-old male patient with dilated cardiomyopathy complicated with heart failure and persistent ventricular tachycardia was treated with nifekalant. The patient was treated with nifekalant for 31 days, which effectively terminated ventricular tachycardia and maintained sinus rhythm, with no clinical adverse reactions. After heart transplantation, postoperative follow-up showed good cardiac function and no arrhythmia. On the basis of nifekalant’s working mechanism, there is a good chance that it can cure ventricular arrhythmia on a long-term basis.

Ferroptosis and its role in cardiomyopathy

Heart disease is the leading cause of death worldwide. Cardiomyopathy is a disease characterized by the heart muscle damage, resulting heart in a structurally and functionally change, as well as heart failure and sudden cardiac death. The key pathogenic factor of cardiomyopathy is the loss of cardiomyocytes, but the related molecular mechanisms remain unclear. Ferroptosis is a newly discovered regulated form of cell death, characterized by iron accumulation and lipid peroxidation during cell death. Recent studies have shown that ferroptosis plays an important regulatory roles in the occurrence and development of many heart diseases such as myocardial ischemia/reperfusion injury, cardiomyopathy and heart failure. However, the systemic association of ferroptosis and cardiomyopathy remains largely unknown and needs to be elucidated. In this review, we provide an overview of the molecular mechanisms of ferroptosis and its role in individual cardiomyopathies, highlight that targeting ferroptosis maybe a potential therapeutic strategy for cardiomyopathy therapy in the future.

Genetic Testing in Patients with Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common inherited heart disease with an estimated prevalence of up to 1 in 200 individuals. In the majority of cases, HCM is considered a Mendelian disease, with mainly autosomal dominant inheritance. Most pathogenic variants are usually detected in genes for sarcomeric proteins. Nowadays, the genetic basis of HCM is believed to be rather complex. Thousands of mutations in more than 60 genes have been described in association with HCM. Nevertheless, screening large numbers of genes results in the identification of many genetic variants of uncertain significance and makes the interpretation of the results difficult. Patients lacking a pathogenic variant are now believed to have non-Mendelian HCM and probably have a better prognosis than patients with sarcomeric pathogenic mutations. Identifying the genetic basis of HCM creates remarkable opportunities to understand how the disease develops, and by extension, how to disrupt the disease progression in the future. The aim of this review is to discuss the brief history and recent advances in the genetics of HCM and the application of molecular genetic testing into common clinical practice.

Apical hypertrophic cardiomyopathy, are low-risk patients really at low risk? A case report

Background

Hypertrophic cardiomyopathy (HCM) is a genetically determined myocardial disease that constitutes the main cause of sudden cardiac death (SCD) in young athletes. Apical HCM (ApHCM) represents a complex subset of patients, whose risk of SCD seems not negligible. Most applied scores likely underestimate the risk of heart events in this subset of patients.

Case summary

We report the case of a 55-year-old man who was admitted in the emergency department after an episode of aborted sudden death due to ventricular fibrillation. The electrocardiogram made at admission was noted for atrial fibrillation and a new-onset left bundle branch block. Emergency coronary angiography was normal. The electrocardiogram was repeated and showed symmetrical and profound inversion of T waves in the lateral leads. Transthoracic echocardiogram and cardiac magnetic resonance revealed left ventricular apical hypertrophy suggestive of apical variant of HCM. A cardiac defibrillator was implanted for secondary prevention of SCD. After 6 months of follow-up no further rhythmic events were noted.

Discussion

Although low, the risk of SCD of ApHCM patients is not negligible. This case illustrates the need for searching of new predictors of rhythmic risk in patients with ApHCM.

Practical Guide to Evaluating Myocardial Disease by Cardiac MRI

OBJECTIVE. A spectrum of pathophysiologic mechanisms can lead to the development of myocardial disorders including ischemia, genetic abnormalities, and systemic disorders. Cardiac MRI identifies different myocardial disorders, provides prognostic information, and directs therapy. In comparison with other imaging modalities, cardiac MRI has the advantage of allowing both functional assessment and tissues characterization in a single examination without the use of ionizing radiation. Newer cardiac MRI techniques including mapping can provide additional information about myocardial disease that may not be detected using conventional techniques. Emerging techniques including MR spectroscopy and finger printing will likely change the way we understand the pathophysiology mechanisms of the wide array of myocardial disorders. CONCLUSION. Imaging of myocardial disorders encompasses a large variety of conditions including both ischemic and nonischemic diseases. Cardiac MRI sequences, such as balanced steady-state free precession and late gadolinium enhancement, play a critical role in establishing diagnosis, determining prognosis, and guiding therapeutic management. Additional sequences-including perfusion imaging, T2*, real-time cine, and T2-weighted sequences-should be performed in specific clinical scenarios. There is emerging evidence for the use of mapping in imaging of myocardial disease. Multiple other new techniques are currently being studied. These novel techniques will likely change the way myocardial disorders are understood and diagnosed in the near future.

The Emergence of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes (hiPSC-CMs) as a Platform to Model Arrhythmogenic Diseases

There is a need for improved in vitro models of inherited cardiac diseases to better understand basic cellular and molecular mechanisms and advance drug development. Most of these diseases are associated with arrhythmias, as a result of mutations in ion channel or ion channel-modulatory proteins. Thus far, the electrophysiological phenotype of these mutations has been typically studied using transgenic animal models and heterologous expression systems. Although they have played a major role in advancing the understanding of the pathophysiology of arrhythmogenesis, more physiological and predictive preclinical models are necessary to optimize the treatment strategy for individual patients. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have generated much interest as an alternative tool to model arrhythmogenic diseases. They provide a unique opportunity to recapitulate the native-like environment required for mutated proteins to reproduce the human cellular disease phenotype. However, it is also important to recognize the limitations of this technology, specifically their fetal electrophysiological phenotype, which differentiates them from adult human myocytes. In this review, we provide an overview of the major inherited arrhythmogenic cardiac diseases modeled using hiPSC-CMs and for which the cellular disease phenotype has been somewhat characterized.

Procollagen type I carboxy-terminal propeptide (PICP) and MMP-2 are potential biomarkers of myocardial fibrosis in patients with hypertrophic cardiomyopathy

BACKGROUND

Whether current proposed biomarkers of myocardial fibrosis (BMFs) actually reflect the changes in fibrous characteristics of myocardial tissue remains unclear. The relation between peripheral BMFs and histological myocardial fibrosis in patients with hypertrophic cardiomyopathy (HCM) has been unknown.

METHODS AND RESULTS

We studied 52 HCM patients who underwent a transaortic extended septal myectomy. Complete medical history was collected, and related examinations were performed. Echocardiography and cardiovascular magnetic resonance were employed to characterize cardiac morphology and function. Procollagen type I carboxy-terminal propeptide (PICP), C-terminal telopeptide of type I collagen (CITP), matrix metalloproteinases (total MMP-2 and total MMP-9), and tissue inhibitor of metalloproteinase 1 (TIMP-1) levels in both plasma and myocardial tissues were determined and compared. Myocardial fibrosis was detected with Masson's trichrome staining, and collagen volume fraction (CVF) was calculated. There was a significant correlation between plasma PICP levels and myocardial PICP contents (r=0.382, P=.007). Besides, plasma PICP (r=0.332, P=.020) levels correlated positively with CVF. In addition, plasma TIMP-1 levels were significantly correlated with myocardial TIMP-1 contents (r=0.282, P=.043). Plasma MMP-2 levels correlated positively with CVF (r=0.379, P=.006). Patients who took calcium channel blockers (CCBs; diltiazem or verapamil) had significantly lower plasma PICP levels, myocardial PICP content, and CVF in comparison with those who did not take CCBs.

CONCLUSIONS

In patients with HCM, plasma PICP and MMP-2 levels quantitatively reflect myocardial fibrosis, suggesting that PICP and MMP-2 may be used as reliable BMFs. CCBs may attenuate cardiac fibrosis in patients with HCM.